1. Field of the Invention
This invention relates to new and improved heat exchanger systems and methods in which the endothermic potential of the evaporation of liquified gas such as nitrogen is used to cool process cooling water.
2. Prior Art
In industrial plants and processes, cooling fluid such as water often is needed. Cooling of such fluids most often is accomplished by the use of radiator-type cooling systems. Unless such systems are designed to accommodate the most severe requirement, e.g. during the hottest days of summer, varying quantities of city water may have to be used to supplement the cooling capacity of the closed cooling system. Such excess amounts of cooling water must be discharged from the system, e.g. to the sewer. However, many governmental regulations prohibit such disposal of cooling fluid, necessitating that the fluid be discharged into on-site treatment facilities. The accompanying expense is unattractive. Over-designing the radiator-type cooling system for assuring necessary cooling capability for, perhaps, only a few days per year is costly in terms of both capital investment and operating expenses.
Closed loop heat exchangers are known in which a first cold fluid in a closed loop functions to lower the temperature of a second cooling fluid.